Reptile softly enters land (8)
I believe the answer is:
terrapin
'reptile' is the definition.
(I know that terrapin is a type of turtle)
'softly enters land' is the wordplay.
'softly' becomes 'p' (short for piano, musical term for softly).
'enters' means one lot of letters goes inside another.
'land' becomes 'terrain' (terrain is land or territory).
'p' placed into 'terrain' is 'TERRAPIN'.
(Other definitions for terrapin that I've seen before include "Little turtle" , "freshwater creature" , "edible, freshwater reptile" , "Aquatic tortoise" , "Water tortoise" .)